Because the IPT found the intelligence sharing to be illegal, anyone, inside or outside the UK, can file a complaint to the IPT and ask if their communications were part of that illegal sharing, and be legally entitled to an answer. [Privacy International's Eric] King explained, “If they don’t find anything, it’s likely they respond ‘no determination’. If they do find something, the IPT is obliged to give a declaration to the individual that their communications were illegally interfered with.”

[Emphasis added]

While the information only applies to information illegally shared with GCHQ by the NSA (and not ASD, CSE, or GCSB), that's still better than we've had before. And if GCHQ had access to NSA data on you, then GCSB almost certainly does to. So this is indirectly a way of finding out which New Zealanders GCSB is illegally spying on through its partner agencies.

To make things easy, Privacy International has started a joint case before the IPT. You can sign up for it here. You'll need to provide an email address and confirm it (Privacy International, understandably, is big on double opt-in). They'll then add your data to their claim before the IPT and try and force an answer for you. It'll probably take a while - the spies don't like being subject to the law - but over ten thousand people have already done it. And if it succeeds, it'll give us our best look at the global spycloud yet.